The present invention relates to implantable spinal fixation systems for the surgical treatment of spinal disorders. More particularly, this invention relates to a transverse rod connector clip for connecting cylindrical rods to each other.
For years doctors attempted to restore stability to the spine by fusion (arthrodesis) of the problem area. This treatment yielded marginal results due to the inherently flexible spinal column. Over the past ten years spinal implant systems have been developed to add stability to the spine to enhance the arthrodesis rates. Such systems often include spinal instrumentation having connective structures such as a pair of plates and/or rods which are placed on opposite sides of the portion of the spinal column which is intended to be fused. These spinal systems consist of screws and hooks for segmental attachment to the spine and longitudinal rods connected to screws or hooks. These components provide the necessary stability both in tension and compression yet yield minimal torsional control.
It has been found that when a pair of spinal rods are fastened in parallel on either side of the spinous process, the assembly can be significantly strengthened by using at least one additional rod to horizontally bridge the pair of spinal rods. A cross brace assembly is disclosed in U.S. Pat. No, 5,084,049. Devices such as these commonly consist of a threaded rod for providing the desired lateral support. The threaded rod is fastened to each of the spinal rods by clamps located on each end of the threaded rod. However, this configuration is bulky and can cause irritation of the patient""s back muscles and other tissue which might rub against the device. A cross brace assembly that fits closer to the spine, preferably in the same general plane as the vertical spinal rods, would reduce the complications associated with bulkier devices.
Most existing transverse connectors consist of rods, plates, and bars linked to the longitudinal rods by coupling mechanisms with set screws, nuts, or a combination of each. These connectors require several components and instruments to build the constructs. Each additional component or instrument required to assemble the connectors adds to the xe2x80x9cfiddle factorxe2x80x9d of the surgical technique. Examples of these transverse connectors include Tranverse Link Device (DLT) and Crosslink manufactured by Sofamor Danek, Trans-Connector manufactured by Synthes, and Modular Cross Connector and Transverse Rod Connector (TRC) manufactured by AcroMed.
Telescopic rod to rod couplers for use in a spinal implant systems have also been described. Prior to the locking member being engaged, the telescoping sections may be easily slid past their extremes and out of engagement with one another. While this is a convenient method of connecting and disconnecting the coupler sections, it can be inconvenient during surgery if the sections accidentally disengage. U.S. Pat. No. 5,275,600 describes a telescopic rod to rod coupler in which the telescopic rod sections are assembled together using a 180 degree twisting motion. This is designed to minimize the risk of the rod sections accidentally disconnecting during the implant procedure.
Presently available spinal fixation systems frequently require careful alignment of the hardware used to connect the components of the spinal instrumentation with each other. A need has thus arisen for improved rod connectors to transversely connect spinal rods without requiring additional manipulation of the spinal instrumentation and to minimize the use of pedicle screws while at the same time reducing requirements to assemble small pieces of hardware during the surgical procedure.
According to one or more aspects of the present invention, a spinal fixation system includes: a first clip body having a pair of opposed spaced apart arcuate rod engaging hooks depending from a first side thereof for engaging a first elongated spinal rod, and a transverse connector extending laterally from a second side thereof; a second clip body having a pair of opposed spaced apart arcuate rod engaging hooks depending from a first side thereof for engaging a second elongated spinal rod, and a transverse connector extending laterally from a second side thereof; and a fastener for securing the transverse connector of the first elongated clip body and the transverse connector of the second elongated clip body to one another.
According to one or more further aspects of the present invention, a spinal fixation system includes: a first clip body having a first pair of opposed spaced apart arcuate engaging hooks depending from a first side thereof for engaging a first elongated spinal rod, and a second pair of opposed spaced apart arcuate engaging hooks depending from a second side thereof for engaging an elongated transverse connector; and a second clip body having a first pair of opposed spaced apart arcuate engaging hooks depending from a first side thereof for engaging a second elongated spinal rod, and a second pair of opposed spaced apart arcuate engaging hooks depending from a second side thereof for engaging the elongated transverse connector.
According to one or more further aspects of the present invention, a spinal fixation system includes: an elongated spinal rod; a transverse member; and a connector having a pair of opposed spaced apart arcuate rod engaging hooks for receiving and engaging the elongated spinal rod, the connector securing the elongated spinal rod and the transverse member in a transverse orientation in which the elongated spinal rod are substantially coplanar.
The transverse connector clips of the present invention can be used to transversely connect spinal rods without requiring additional manipulation of the spinal instrumentation. Because the clips of the present invention do not require any additional locking mechanism, they reduce the assembly of small pieces of hardware during the surgical procedure.